The veterinary studies area conducts investigations using veterinary morbidity and mortality data from university teaching hospitals in North America. the Armed forces Institute of Pathology. NCI's Registry of Experimental Cancers. and other sources as available. These studies investigate the role of genetic and environmental factors on the etiology of cancer in animals and generate hypotheses for testing in companion humans and other human populations. Major areas of interest include the effects of household exposure to pesticides among pet dogs and their companion humans. Another area of focus are studies of cancer and other conditions among U.S. military working dogs (MWD) who served in Vietnam relative to that among other MWDs who served elsewhere. with linkage to health conditions that occurred among their human handlers (N=20,000). Other studies of the effects of the Vietnam experience are being conducted using a cohort of West Virginia residents who served in Vietnam (N=41,000) relative to the health experience among those who did not serve in Vietnam during their military service (N=42.000). Previous work has shown a significant twofold excess of testicular seminoma among Vietnam service MWDs and independently. a significant twofold excess association of Vietnam service and testicular cancer among human patients seen collectively at three Washington. D.C. area hospitals. Present work shows a significant association of testicular seminoma and ever service in I Corps. the Combat Tactical Zone where the highest elevations of risk have been identified within Vietnam among various human studies. further. benign prostatic hyperplasia likewise is significantly elevated among Vietnam service MWDs. particularly among those who served in I Corps; canine prostatic carcinoma is also significantly associated with Vietnam service.